Trying to reach a managed mobile device, fails and you get the error message "APNs is not reachable"
This could happen due to various reasons such as ,
TCP port # 2195 should be opened in the Desktop Central firewall, this will allow the Desktop Central Server to communicate with the APNs.
Proxy Not Configured:
If the network in which Desktop Central server is installed has a proxy, ensure that the proxy settings are configured. Verify the user name and the password for proxy authentication, so that the Server can reach the APNs
If the specific ports are open and the proxy is configured properly, then you need to check the APNs certificate. Verify the APNs certificate if it is valid, and check if the APNs file format is .p12. If you still have problems with your APNs certificate, you need to re-generate a new APNs certificate and upload them.
Applies to: Scanning the mobile device, Distributing Apps, Associating Profiles
Keywords: MDM scanning, Associating profiles, APNs, Mobile Device Management